1. Field of the Invention
The present invention relates to an operational amplifier. More particularly, the present invention relates to a dynamic biasing amplifier, dynamic biasing apparatus and method.
2. Description of Related Art
FIG. 1 is a block diagram of a conventional amplifier. In a conventional amplifier, a current source 110 supplies a constant current IBP to a DC bias generator 120. The DC bias generator 120 then generates a DC bias voltage VB1-1˜VB1-n to an operational amplifier 130 based on the constant current IBP. The operational amplifier 130 performs signal amplification based on the bias point provided by the DC bias generator 120, so as to amplify the input signal Vi into an output signal Vo.
If the operational amplifier has a relatively large load capacitance (CL), the DC bias generator 120 requires a higher DC bias current IBP, such that the operational amplifier 130 can achieve the required switching speed. It turns out that the conventional amplifier has a drawback of high power consumption in the steady state since the DC bias current IBP must be very large (to meet the requirements of the switching speed) in high operation or driving a heavy load. On the other hand, if the DC bias current IBP of the conventional amplifier is small in order to save power, the operation speed will become very low.